PB2466: PERIPHERAL BLOOD AS GRAFT SOURCE FOR APLASTIC ANEMIA TRANSPLANT: OUTCOMES OF YOUNG ADULTS AND ADULTS IN A MEXICAN PUBLIC HOSPITAL
Authors: Guillermo Sotomayor Duque, Severiano Baltazar, Roxana Saldaña Vazquez, Humberto Guerra Ramos, Rosa Elva Leon Cantú, Roberto Hernandez, Gerardo Luna Lopez
Journal: HemaSphere (2023)

Topic: 22. Stem cell transplantation - Clinical Background: Aplastic anemia (AA) is a benign hematologic pathology characterized by an autoimmune T-cell mediated attack on marrow niche and its consequent failure. Allogeneic transplant is the curative treatment of choice for patients under 40 years of age with a matched related donor (MRD); for patients who do not have an identical donor, or who have failed immunosuppressive therapy; related haploidentical transplantation has become a feasible option in several centers around the world. Aims:Describe results of patients over 15 years old with AA undergoing MRD and haploidentical allogeneic transplantation in our center. Methods:retrospective study in IMSS UMAE 25 Monterrey, Mexico. Descriptive analysis was performed with measures of central tendency, medians, and frequencies. Survival analysis was performed with the Kaplan Mier method and comparative with log rank with a significant p value <0.05. Results: A total of 17 patients were included in a period from January 2017 to January 2023; 9 male (56%) and 8 female (44%) with a median age of 32 years (15-58). Only six patients had a MRD, eleven underwent an haploidentical transplant. Median follow-up was 8 months (1-20). Conditioning was based on a non-myeloablative scheme (ATG-Flu-Cy) in 83% and RIC scheme (Bu-Flu-Cy) in 17%. GVHD prophylaxis, was based on methotrexate and cyclosporine for the MRD group and tacrolimus, mycophenylate mofetil and post transplantation cyclophosphamide for the haploidentical one. Median CD34+ was 12.74 x 106 (6.9-21.6); graft source was peripheral blood in all patients and the donor was male in 83% of cases. Blood group compatibility was 94%. Previous to transplantation 3 patients underwent desensitization for donor-specific anti-HLA antibodies using a protocol that included plasma exchange, IVIg, Rituximab and MMF. Median chimerism of 99% (2-100%) was reach by day 30. Primary graft failure occurred in 1 patient and secondary failure in another one. CMV reactivation befall in 29%. Grade I/II GVHD was diagnosed in 5 patients (29%), nopatient developed grade III/IV GVHD. The median follow-up was 8 months (1-20). Overall survival (OS) was 80% at 20 months in all patients; 83% in the MRD group and 81% for the haploidentical (log rank 0.06, p=0.80). Patients younger than 40 years had OS at 20 months of 100% and for those older than 40 years it was 44% (log rank 6.78, p=0.0091). Transplant related mortality (TRM) was 18% (one patient due to primary graft failure, one due to CMV infection and one patient due to cerebral hemorrhage). Summary/Conclusion:In our small cohort peripheral blood as graft source proved no difference in OS and GVHD frequency in either group, with a TRM below 20%. Patients under 40 years of age benefits the most from transplantation in a timely and early manner.Keywords: Young adult, Peripheral blood stem cell transplant, Aplastic anemia